why I will pay $299 right now If maybe on BF this year they will lower the price or add a game?
Nintendo does not usually lower console prices on Black Friday/holiday time. Sometimes they'll do a BUNDLE with a game, but the odds of Nintendo dropping the Switch from $299 is insanely low this year. Maybe just maybeeee a retailer will choose to do that on their own, however that's extremely unlikely if the Switch continues selling out until that point.
No one is going to reduce the price on something if they don't have it available for you to buy it on the shelves. Obviously that's pretty far off, but with Skyrim and Mario coming out I would be surprising if mid Fall Nintendo (or retailers) have any incentive to lower the price then. Best case scenario is a holiday bundle at $299 with Mario included. Although based on how Nintendo treated the Wii U (and even the 3DS for the most part, still being almost $200), I find it unlikely